Project Summary/Abstract Polychlorinated biphenyls (PCBs) are ubiquitous and persistent organic pollutants that adversely affect human health. Although industrial production of PCBs has been discontinued, they remain a pressing environmental problem due to their slow biodegradation and high lipophilicity. These properties enable PCBs to bio-accumulate in food chains leading to high tissue levels in organism important for human consumption. Once in the body, PCBs accumulates in various organs leading to inflammation and activation of the transcription factor NF-?B. NF-?B is a driver of inflammation and has been linked to a multitude of diseases such as inflammatory bowel disease, cancer and diabetes. Despite dietary exposure being the main route of exposure to PCBs, the human gastrointestinal tract has been widely ignored when studying the pro-inflammatory effects of PCBs. This is a significant oversight given that the intestinal epithelial cells (IECs) are simultaneously exposed to the inflammatory effects the gut microbiota, which are also affected by the PCBs. The functional consequences of PCBs effects on the microbiome have also yet to be studied. This is vital information given the widespread influence of the microbiome. The proposed studies will interrogate interaction between PCBs, IECs, and the microbiota with particular focus on the mechanism by which PCB153 (the most prevalent PCB in the environment) exerts its effects. Exposure to PCB153 has been shown to lead to an increased intestinal permeability along with signs of gross intestinal inflammation and changes in the microbiome. I hypothesize that PCB153 causes intestinal inflammation and increases gut permeability via genotoxic activation of NF-?B and the creation of a pro-inflammatory gut microbiome. To interrogate this, specific aim 1 will look at the effects of PCB153 specifically on the IECs, both in vitro and in vivo. Intestinal cell lines along with gnotobiotic mice, mice entirely lacking a microbiome, will be used to determine the extent and mechanism of NF-?B activation by PCB153 in the absence of the microbiome. Specificity to the proposed mechanism will be established using a chemical inhibitor of NF-?B. Specific aim 2 will determine the functional consequences of PCB153's effect on the microbiome. PCB-exposed microbiomes will be transplanted into gnotobiotic mice and then challenged with a pro-inflammatory agent. Their levels of inflammation will be compared with those of mice transplanted with PCB-nave microbiomes shedding light on the pro-inflammatory effects of the PCB-exposed microbiome on the host. These studies will establish the importance of NF-?B in the inflammatory and permeability changes caused my PCB153 in the gut. Importantly, they will be able to draw clear conclusions about the distinct roles of the microbiota and IECs. This knowledge, will depict new routes of investigation and potential therapies for humans and other organisms exposed to organic pollutants.